script loops when trying to render issue 1074

[hallvors]

https://webcompat.com/issues/1074 seems to send some part of our JS (the Prism highlighter/tokenizer?) into a never-ending loop, causing a "slow script" dialog.

If there's a newer version of Prism we can try upgrading - else we need to dig into the tokenizer logic. I'm happy to do that :)

[karlcow]

Wondering if it's because of the opening brace which is not closed. That would be a funny bug.

[hallvors]

The cause here is actually a regexp used to look for a closing tag. The DIV tag in my comment isn't closed, and processing this regular expression will never finish:
/</?[\w:-]+\s_(?:\s+[\w:-]+(?:=(?:("|')(?[\w\W])?\1|[^\s'">=]+))?\s)_/?>/gi

[hallvors]

(And it's not Firefox's fault - this thing fails in all browsers. Too many lookaheads, I guess..)

[miketaylr]

@hallvors can you check to see if the latest has a fix? https://github.com/PrismJS/prism

[hallvors]

The problematic regexp is still there:
https://github.com/PrismJS/prism/blob/b1fd5bdcee9c6203748286d13d6299f6ca90d903/components/prism-markup.js#L7
Maybe @LeaVerou and @PrismJS know if it's a known issue..

[miketaylr]

Probably worth filing a proper bug upstream then. Or submitting a patch. :)

[miketaylr]

(I went ahead and edited your comment to close the div as a workaround).

[LeaVerou]

This is very odd. Can you reproduce in Prism’s test drive page? If so, could you file an issue on Prism’s repo? This is serious, and would be very high priority.

[miketaylr]

Thanks @LeaVerou -- reported.